RPR 109413 is a highly purified, liquid intravenous immunoglobulin (IVIG) product. Its primary difference from currently marketed IVIG products is that it includes a wet heat treatment (pasteurization) as an additional safeguard against virus particles. The present study is part of a double-blind randomized phase II comparison of the safety, tolerance, efficacy, and biological half-life of RPR 109413 and Gamimune N (10% solutions) administered intravenously at a dose ranging from 200 mg/kg to 600 mg/kg to approximately 81 patients from up to ten centers with primary or secondary immune deficiency characerized by defective antibody synthesis.